1. Field of the Invention
This invention relates to a light modulator, particularly a light modulator for modulating light by controlling take-up of a guided wave from a wave guide. This invention also relates to a wave guide device, particularly a wave guide device comprising a wave guide layer formed of a thermo-optic material whose optical refractive index changes with heat so that a wave guide inside of the wave guide layer is radiated therefrom for use in light beam scanning, light modulation or the like.
2. Description of the Prior Art
As light modulators for external modulation of a light beam such as a laser beam, electro-optic modulators (EOM), acousto-optic modulators (AOM) and the like have heretofore been known. In recent years, wave guide type light modulators using a thermo-optic material have also been proposed. One of the wave guide type light modulators is described in Appl. Phys. Lett., Vol. 45, P840 (1984). In this light modulator, the mode is switched between guided mode and radiation mode by the controlled application of an electric field or the like to the wave guide, and wave radiated out of the wave guide is thereby modulated.
However, the light modulator having the aforesaid configuration has the drawback that, since the efficiency of wave take-up from the wave guide in the radiation mode is low, a substantially high extinction ratio is not obtained.